Constant GPU_DDL 

pub const GPU_DDL: &str = "
CREATE TABLE IF NOT EXISTS launches (
    id              INTEGER PRIMARY KEY,
    session_id      TEXT NOT NULL REFERENCES sessions(id),
    kernel_name     TEXT NOT NULL,
    duration_us     REAL NOT NULL,
    grid_x          INTEGER, grid_y INTEGER, grid_z INTEGER,
    block_x         INTEGER, block_y INTEGER, block_z INTEGER,
    stream_id       INTEGER,
    start_us        REAL,
    correlation_id  INTEGER,
    layer_id        INTEGER REFERENCES layers(id)
);
CREATE INDEX IF NOT EXISTS idx_launches_kernel ON launches(session_id, kernel_name);
CREATE INDEX IF NOT EXISTS idx_launches_start  ON launches(session_id, start_us);
CREATE INDEX IF NOT EXISTS idx_launches_stream ON launches(session_id, stream_id);

CREATE TABLE IF NOT EXISTS metrics (
    session_id                TEXT NOT NULL REFERENCES sessions(id),
    kernel_name               TEXT NOT NULL,
    occupancy_pct             REAL,
    compute_throughput_pct    REAL,
    memory_throughput_pct     REAL,
    registers_per_thread      INTEGER,
    shared_mem_static_bytes   INTEGER,
    shared_mem_dynamic_bytes  INTEGER,
    l2_hit_rate_pct           REAL,
    achieved_bandwidth_gb_s   REAL,
    peak_bandwidth_gb_s       REAL,
    boundedness               TEXT,
    layer_id                  INTEGER REFERENCES layers(id),
    PRIMARY KEY (session_id, kernel_name)
);

CREATE TABLE IF NOT EXISTS transfers (
    id              INTEGER PRIMARY KEY,
    session_id      TEXT NOT NULL REFERENCES sessions(id),
    kind            TEXT NOT NULL,
    bytes           INTEGER,
    duration_us     REAL,
    start_us        REAL,
    stream_id       INTEGER,
    layer_id        INTEGER REFERENCES layers(id)
);

CREATE TABLE IF NOT EXISTS ops (
    id              INTEGER PRIMARY KEY,
    session_id      TEXT NOT NULL REFERENCES sessions(id),
    name            TEXT NOT NULL,
    module_path     TEXT,
    cpu_time_us     REAL,
    gpu_time_us     REAL,
    input_shapes    TEXT,
    layer_id        INTEGER REFERENCES layers(id)
);

CREATE TABLE IF NOT EXISTS op_kernel_map (
    session_id      TEXT NOT NULL REFERENCES sessions(id),
    op_id           INTEGER NOT NULL REFERENCES ops(id),
    kernel_name     TEXT NOT NULL,
    PRIMARY KEY (op_id, kernel_name)
);
";

GPU domain tables (CUDA launches, ncu metrics, memcpy transfers, framework ops). From gdbg’s current schema, with session_id added.